Pledge of Allegiance problem in school

Hiya. My name is Ash...I go to a high school in the state of Georgia, and I am currently taking AP US History.I do not say the pledge, and I do not stand.I do not say it because I know America is not "under God" and I know there is not "liberty and justice for all."I choose not to stand because I don't want to stand for a country, that I believe, does not stand for me.I have not stood for the pledge since 8th grade, and I'm currently in 11th. I have never had any problems until now.I have not stood in my APUSH class all year and my teacher recently just caught me sitting.He told me to stand.I said no.As soon as the pledge was over, he took me out of the class and chewed me out. He said that as long as I'm in his class I must stand, that it is illegal to sit, and he was going to get me kicked out of his class.Obviously, none of that was true. I'm still in the class.I went to an administrator about the issue and he talked to my teacher. Nothing was done in my favor.Every morning I must sit outside his classroom door in the hallway until the pledge is over.I feel very discriminated against. I should not have to sit/stand outside his door. I know this is wrong of him to do and I am very unhappy with it.This is our only AP teacher.What should I do?My mom told me to stand anyway, and my brother called me an idiot.Don't tell me to just stand, because I'm not going to go against something I believe in just for some school.Is there anything I could do?